Plasma Processing Apparatus, Plasma Processing Method and Storage Mediuim

ABSTRACT

A plasma processing apparatus includes a first electrode and a second electrode so arranged in the upper portion of a processing chamber as to face a mounting table, a gas supply unit for supplying a processing gas between the first electrode and the second electrode, a RF power supply unit for applying a RF power between the first electrode and the second electrode for converting the process gas supplied between the electrodes into a plasma, and a gas exhaust unit for evacuating the inside of the processing chamber to a vacuum level from the lower portion of the processing chamber. Since the electron temperature in the plasma is low near a substrate on the mounting table, damage to the substrate caused by the plasma can be suppressed. In addition, since a metal can be used as a material for the processing chamber, the processing chamber can have good temperature controllability.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a Divisional application of and claims thebenefit of priority from co-pending U.S. application Ser. No.12/523,212, filed Aug. 20, 2009, which is a national stage applicationof PCT/JP2007/075076, filed Dec. 27, 2007, which claims the benefit ofpriority to Japanese Patent Application No. 2007-006206, filed Jan. 15,2007, the entire contents of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a plasma processing apparatus, a plasmaprocessing method and a storage medium storing a program for executingthe plasma processing method.

BACKGROUND OF THE INVENTION

For example, in a manufacturing process of a semiconductor device or aliquid crystal device, a substrate is subjected to a process such asetching, sputtering, CMP (Chemical Vapor Deposition) or the like. Inthose processes, a plasma processing apparatus using plasma is widelyused. In the plasma processing apparatus, a processing gas is injectedinto a processing chamber accommodating the substrate and, then, theprocessing gas is converted to plasma and activated, so that each of theabove-mentioned processes is performed on the substrate.

Hereinafter, various plasma processing apparatuses are explainedspecifically. FIG. 17 shows a parallel-plate dual-RF (Radio Frequency)type plasma etching apparatus 101 which generates capacitively-coupledplasma (CCP) by using a RF electric field formed between bothelectrodes. The plasma etching apparatus 101 includes a processingchamber 102 as a vacuum chamber, a mounting table 103 for mountingthereon a wafer W and serving as a lower electrode within the processingchamber 102, and a gas shower head 105 having a plurality of gas supplyholes 104 and forming a ceiling plate of the processing chamber 102.

Sidewalls of the processing chamber 102 are made of, e.g., aluminum, andinner surfaces of sidewalls are covered and insulated with a ceramicsuch as yttrium oxide (Y₂O₃) or alumite (Al₂O₃) or the like. Moreover,within the sidewalls there are coolant flow channels 106 circling alongthe sidewalls to control a temperature thereof.

The gas shower head 105 is provided at its lower side with an upperelectrode 107 which includes a metal base 108 made of, e.g., aluminum,and a conductive plate 109 made of, e.g., silicon, which is located on alower surface of the metal base 108. Although not shown in FIG. 17,within the metal base 109, there are coolant flow channels to control atemperature of the gas shower head 105.

A reference numeral 110 in FIG. 17 refers to a gas supply source whichsupplies the gas shower head 105 with processing gas which, in turn, issupplied to the wafer W through the gas supply holes 104. A referencenumeral 111 in FIG. 17 refers to a gas exhaust line which exhausts thegas in the processing chamber 102, thereby bringing the pressure of thechamber 102 into a predetermined value. Reference numerals 112, 113 inFIG. 17 refer to first and second RF power supplies respectively. Ifeach of the first and second RF power supplies 112, 113 turns on afterthe processing gas has been supplied to the processing chamber, a RFpower of, e.g., 13 MHz to 60 MHz from the first RF power supply 112 isapplied to the upper electrode 107 to generate plasma under the upperelectrode 107 as shown in a dotted line of FIG. 17 and activate theprocessing gas, and at the same time, a RF power of, e.g., 0.38 MHz to13 MHz from the second RF power supply 113 is applied to the mountingtable 103 to generate a biasing potential which attracts ions in theplasma toward the wafer W to etch the surface of the wafer W.

In the plasma etching apparatus 101, the gas shower head 105 and theprocessing chamber 102 are made of metal materials and have the coolantflow channels to cool down them, so that the temperatures of the gasshower head 105 and the processing chamber 102 can be controlled.Accordingly, even when a plurality of wafers W of a same lot isprocessed sequentially, temperature increasing due to accumulated heatin each sequential process can be avoided. As a result, processingvariations on the wafer W due to the heat from the gas shower head 105and the processing chamber 102 can be avoided. Further, even when, e.g.,a processing gas whose components are readily deposited in a hightemperature level is used, deposition of the components can besuppressed by controlling the temperatures of the gas shower head 105and the processing chamber 102. Consequently, it is possible to suppressthe likelihood that deposits become particles to contaminate the waferW.

Following is a description of a plasma etching apparatus 120 as shown inFIG. 18. The plasma etching apparatus 120 generates plasma by usingmicrowaves. In FIG. 18, for elements or units having the sameconfiguration as those of the plasma etching apparatus 101 shown in FIG.17, the same reference numerals are used. A reference numeral 121 inFIG. 18 refers to a first gas supply unit which forms a ceiling plate ofa processing chamber 102 and is made of a ceramic of, e.g., siliconoxide (SiO₂) or Al₂O₃ or the like so as to transfer microwaves to alower surface thereof as will be explained later. The first gas supplyunit 121 also forms a gas shower head. Provided in lower parts of thefirst gas supply unit 121 are first gas supply holes denoted as areference numeral 122. A reference numeral 123 refers to a gas supplysource for supplying a plasma generating gas. The gas supply source 123supplies the plasma generating gas 122 into the processing chamberthrough a gas path 124 provided within the first gas supply unit 121and, then, the first gas supply holes 122.

A reference numeral 125 in FIG. 18 refers to a second gas supply unitwhich partitions the space between the first gas supply unit 121 and amounting table 103, and also forms a gas shower head. The second gassupply unit 125 includes a plurality of second gas supply holes 126. Areference numeral 127 refers to a gas supply source for supplying aprocessing gas such as an etching gas or a depositing gas. Theprocessing gas supply source 127 supplies the processing gas toward thewafer W through a gas path 128 provided within the second gas supplyunit 125 and, then, the second gas supply holes 126. A reference numeral129 refers to through-holes penetrating through the second gas supplyunit 125 so as to supply the etching gas from the first gas supply unit121 toward the wafer W.

A reference numeral 131 in FIG. 18 refers to a microwave generating unitwhich supplies microwave having a frequency of, e.g., 2.45 GHz or 8.3GHz. The microwaves move through a transfer unit 132 and the first gassupply unit 121, and, then, are emitted toward a processing space underthe first gas supply unit 121, so that the plasma generating gas fromthe first gas supply unit 121 is converted to plasma as shown by adotted line of FIG. 18. Thereafter, the plasma-converted plasmagenerating gas goes down and, then, converts the processing gas suppliedfrom the second gas supply unit 125 to plasma, so that theplasma-converted processing gas processes the surface of the wafer W.

Following is a description of a plasma etching apparatus 141 as shown inFIG. 19A. The plasma etching apparatus 141 generates inductively-coupledplasma (ICP) and includes a processing chamber 142 made of quartz.Reference numerals 143, 144 in FIG. 19A refer to nozzles for supplying aprocessing gas. As shown in FIG. 19B, a coil 145 winds around upperportions of the processing chamber 142. One end of the coil 145 isconnected to a RF power supply 112 and the other end thereof isconnected to ground. If an electric current is applied to the coil 145after the processing gas has been supplied from the nozzles 143, 144, anelectric field is generated in the processing chamber 142 to generateplasma as shown by a dotted line in FIG. 19A.

However, because in the parallel-plate electrode type(capactively-coupled type) plasma etching apparatus 101 of FIG. 17, theRF power is applied directly between the upper electrode 107 and themounting table 103 serving as the lower electrode, the electrontemperatures in the plasma in the apparatus 101 of FIG. 17 becomesincreased to, e.g., 3 eV to 4 eV compared with the microwave plasmaetching apparatus 120 or the inductively-couple plasma etching apparatus141. Accordingly, in the etching apparatus 101, ions or the like havinga high level energy collides with the wafer W, which may causesignificant damage to the wafer W.

Additionally, in the etching apparatus 101, there appear interferencesof the two RF powers, since the plasma generating RF power is applied tothe upper electrode 107 serving as a ceiling plate of the processingchamber, and, at the same time, the biasing RF power is applied to themounting table 103 serving as the lower electrode. As a result, awaveform of the RF power applied to the mounting table 103 is distorted,and, hence, it is difficult to control the RF power. Moreover, this isreason why variations of energy distribution of ions in the plasma onthe surface of the wafer W occur. On the other hand, such variations canbe controlled to be negligible by adjusting parameters such asfrequency, power level and the like of each of the RF power supplies112, 113. However, because this approach will need to control as manyparameters as possible, not only it will take long time but also manyparameters must be fixed for suppressing the variations, therebydecreasing the degree of freedom in the plasma processing. Moreover, ashape of ion collision distribution where a horizontal axis representsan ion energy level and a vertical axis represents a collision frequencyof ions against the substrate corresponds to a shape of the waveform ofthe biasing RF power if the biasing RF power does not interfere with theplasma generating RF power when the biasing RF power is applied to themounting table 103. Thus, an adequate shape of the ion collisiondistribution shall be selected based on the processing process. However,when the biasing and plasma generating RF powers interfere with eachother, such a selection will be not performed with a good precision.

To solve the above problem, a gap between the upper electrode 107 andthe mounting table 103 can be as large as possible. However, in thisapproach, the plasma itself may not be generated, making it impossibleto perform the normal processing.

On the other hand, in the microwave plasma etching apparatus 120 of FIG.18, the microwaves emitted from the ceiling plate do not interfere withthe biasing RF power applied to the mounting table 103 and, hence, thewaveform of the biasing RF power applied to the mounting table 103 isnot distorted. Further, the electron temperature beneath the first gassupply unit 121 becomes as high as 5 eV to 10 eV, whereas the electrontemperature near the wafer W becomes as low as 1 eV to 2 eV. This isbecause the processing gas near the wafer W is converted to the plasmaby actions of the plasma generating gas supplied from the first gassupply unit 121. Accordingly, the energy of ions or electrons actingtoward the wafer W is low, so that the wafer damage by the plasma can besuppressed.

However, in the microwave plasma etching apparatus 120 of FIG. 18, thefirst gas supply unit 121 forming the ceiling plate of the apparatus 120is made of the ceramic so as to effectively transfer the microwaves tothe lower surface thereof, but it is difficult to control thetemperature of the first gas supply unit 121. This is because a heatcapacity of the ceramic is larger than that of a metal such as aluminumor the like. Therefore, when a plurality of the wafers W within the samelot is processed sequentially, the heat from each sequential process isaccumulated onto the first gas supply unit 121. As a consequence, theaccumulated heat makes an influence on the processing of the wafer W,which may cause processing variations between wafers. In addition, asmentioned above, when, e.g., the processing gas whose components arereadily deposited in a high temperature level is used, the deposits ofthe gas become particles to contaminate the wafer W.

Further, in the microwave plasma etching apparatus 120 of FIG. 18, aninner space of the processing chamber 102 becomes vacuum state duringthe processing and, hence, a diffusibility of the processing gasincreases. For this reason, it is likely that some of the processing gassupplied from the second gas supply unit 125 does not diffuse toward thewafer W but diffuses into a space near the first gas supply unit 121through the through-holes 129, and, then, turns back toward the wafer W.Further, as mentioned above, the electron temperature near the first gassupply unit 121 is higher than the electron temperature near the waferW. Accordingly, a dissociation level at which molecules of theprocessing gas are dissociated into ions or radicals, an energy leveland, hence, a reaction level with the wafer W are different between theprocessing gas supplied directly from the second gas supply unit 125onto the wafer W and the processing gas that is supplied from the secondgas supply unit 125 and diffuses into the space near the first gassupply unit 121, and, then turns back toward the wafer W. In conclusion,wafer in-plane variations and/or wafer to wafer variations of theprocessing may occur.

Further, in the inductively-couple plasma etching apparatus 141 of FIG.19A, a RF current is not applied directly into the processing chamber142 and, hence, the waveform of the RF power supplied to the mountingtable 103 is not distorted. However, because a heat capacity of thequartz is larger than that of a metal such as aluminum or the like, itis difficult to control the temperature of the processing chamber 142made of the quartz. Accordingly, the heat from each wafer processing isaccumulated into the sidewalls and the ceiling plate of the processingchamber 142. As a consequence, there may occur the wafer to waferprocessing variations in the same lot as in the microwave plasma etchingapparatus 120. In addition, as in the microwave plasma etching apparatus120, when, e.g., the processing gas whose components are readilydeposited in a high temperature level is used, the deposits of the gasbecome particles to contaminate the wafer W.

Further, in the inductively-couple plasma etching apparatus 141, anelectric field is generated in an upper part of the processing chamber142 and, hence, it is impossible to supply the processing gas by usingthe gas shower head. For this reason, the processing gas is suppliedfrom nozzles in the etching apparatus 141. Thus, it is difficult touniformly supply the gas on the wafer W, so that wafer in-planeuniformity in the etching process decreases.

In conclusion, each of the above-mentioned plasma processing apparatuseshas at least one among defections including the difficulty to controlthe temperature of the sidewalls and the ceiling plate of the processingchamber, the substrate damage by the plasma, the non-uniformity of thegas supply to the substrate, and the difficulty to control the waveformof the RF power.

SUMMARY OF THE INVENTION

In view of the above, the present invention provides a plasma processingapparatus and method for easily controlling the temperature of thesidewalls of the processing chamber and capable of suppressing thesubstrate damage by the plasma.

In accordance with a first aspect of the present invention, there isprovided a plasma processing apparatus having a processing chamber and amounting table provided within the processing chamber for processing asubstrate mounted on the mounting table by plasma which processing gasis converted to, the apparatus including: first and second electrodesprovided in an upper portion of the processing chamber so as to face themounting table; a gas supply unit for supplying the processing gas intobetween the first and second electrodes; a radio frequency (RF) powersupply unit connected to at least one of the first and second electrodesfor applying a RF power between the first and second electrodes so thatthe processing gas supplied into between the first and second electrodesis converted to the plasma; and a gas exhaust unit coupled to a lowerportion of the processing chamber for exhausting the inside of theprocessing chamber to a vacuum level.

The gas supply unit is located above the first and second electrodes,and faces the mounting table, and has a plate-type body in which aplurality of gas supply holes are formed. The gas supply unit isprovided with a temperature adjustment mechanism for adjusting atemperature of the gas supply unit. The processing chamber is made of ametal and is provided with a temperature adjustment mechanism foradjusting a temperature of the processing chamber. Each of the first andsecond electrodes has a plurality of teeth which horizontally extend(extend abreast) in parallel with each other, and the teeth of the firstelectrode and the teeth of the second electrode are alternatelyarranged. Each of the first and second electrodes has a base, the baseof the first electrode and the base of the second electrode facing eachother in a horizontal direction, and the teeth of the first electrodeand the teeth of the second electrode respectively extend from the baseof the first and second electrode so as to face each other.

The first and second electrodes are formed as concentric ring-shapemembers, having different diameters. At least one of the ring-shapemember forming the first electrode and the ring-shape member forming thesecond electrode is provided in plural, the ring-shape member formingthe first electrode and the ring-shape member forming the secondelectrode are alternately disposed, and distance between the neighboringring-shape members gets smaller as it goes away from the center of thering-shape members.

The gas supply unit is formed as the entirety or a portion of one of thefirst and second electrodes. A plurality of linear protrusions, whichhorizontally extend (extend abreast) in parallel with each other spacedapart from each other, are arranged at a lower surface of the gas supplyunit, the linear protrusions are formed as a part of one of the firstand second electrodes, and the other of the first and second electrodesis disposed under the linear protrusions or at a side thereof. Thepluralities of the linear protrusions are formed in a shape of a ring orstraight-line. The first and/or second electrodes are provided with aplurality of holes for making an electric potential of the entiresurface thereof uniform, to the holes penetrating through thecorresponding first and/or second electrodes.

The RF power supply is a first RF power supply, a lower electrode isprovided in the mounting table, and a second RF power supply for biasingand attracting the plasma due to the processing gas toward the substrateis connected to the lower electrode. The first and second electrodeshave flow channels for a temperature adjustment fluid for adjustingtemperatures of the first and second electrodes, respectively.

In accordance with a second aspect of the present invention, there isprovided a plasma processing method for processing a substrate by plasmadue to a processing gas, the method includes: mounting the substrateonto a mounting table provided within a processing chamber; supplyingthe processing gas into between first and second electrodes provided inan upper portion of the processing chamber so as to face the mountingtable; applying a RF power between the first and second electrodes sothat the processing gas supplied into between the first and secondelectrodes is converted to the plasma; and exhausting the inside of theprocessing chamber from a lower portion of the processing chamber to avacuum level. The processing gas is supplied into between the first andsecond electrodes through a plurality of gas supply holes formed througha plate-type body that is located above the first and second electrodesto face the mounting table.

A storage medium storing a computer-readable program for performing aplasma processing method for processing a substrate by plasma due to aprocessing gas, the method includes: mounting the substrate onto amounting table provided within a processing chamber; supplying theprocessing gas into between first and second electrodes provided in anupper portion of the processing chamber so as to face the mountingtable; applying a RF power between the first and second electrodes sothat the processing gas supplied into between the first and secondelectrodes is converted to the plasma; and exhausting the inside of theprocessing chamber from a lower portion of the processing chamber to avacuum level.

In accordance with the present invention, the first and secondelectrodes are provided in an upper portion of a processing chamber anda RF power is applied between them, so that an electron temperature inplasma near a substrate on the mounting table becomes lower toeffectively suppress the substrate damage by the plasma. Further, ametal is used as a material of the processing chamber to easily controla temperature of the processing chamber as in the parallel-plateelectrode type plasma processing apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical cross-sectional side view showing a plasma etchingapparatus in accordance with a first embodiment of the presentinvention.

FIG. 2 is a transverse cross-sectional plan view showing a combelectrode included in the plasma etching apparatus.

FIG. 3 is a perspective view showing coolant flow channels provided inthe comb electrodes.

FIG. 4 describes the state in which the plasma etching apparatusperforms an etching process.

FIG. 5 is a vertical cross-sectional side view showing a plasma etchingapparatus in accordance with another embodiment of the presentinvention.

FIG. 6 is a perspective view showing a configuration of electrodesincluded in the plasma etching apparatus of FIG. 5.

FIG. 7 describes the state in which the plasma etching apparatus of FIG.5 performs the etching process.

FIG. 8 is a vertical cross-sectional side view showing a plasma etchingapparatus in accordance with still another embodiment of the presentinvention.

FIG. 9 is a perspective view showing a configuration of electrodes and agas shower head included in the plasma etching apparatus of FIG. 8.

FIG. 10 describes the state in which the plasma etching apparatus ofFIG. 8 performs the etching process.

FIG. 11 is a vertical cross-sectional side view showing a plasma etchingapparatus in accordance with still another embodiment of the presentinvention.

FIG. 12 is a perspective view showing a configuration of electrodesincluded in the plasma etching apparatus of FIG. 11.

FIG. 13 is a vertical cross-sectional side view showing a plasma etchingapparatus in accordance with still another embodiment of the presentinvention.

FIG. 14 is a perspective view showing a configuration of electrodeincluded in the plasma etching apparatus of FIG. 13.

FIG. 15 is a vertical cross-sectional side view showing a plasma etchingapparatus in accordance with a still another embodiment of the presentinvention.

FIG. 16 is a perspective view showing a configuration of electrodesincluded in the plasma etching apparatus of FIG. 15.

FIG. 17 is a vertical cross-sectional side view showing a conventionalplasma etching apparatus.

FIG. 18 is a vertical cross-sectional side view showing anotherconventional plasma etching apparatus.

FIGS. 19A and 19B are a vertical cross-sectional side view and aperspective view showing still another conventional plasma etchingapparatus.

DETAILED DESCRIPTION OF THE EMBODIMENT First Embodiment

Referring to FIG. 1, a configuration of a plasma etching apparatus 1 inaccordance with a first embodiment of the present invention will bedescribed. The plasma etching apparatus 1 processes, e.g., a rectangulartype substrate B such as an FPD (Flat Panel Display) or the like. Theplasma etching apparatus 1 includes a tubular processing chamber 11having enclosed sealed inner processing space, a mounting table 2installed at a center region in a lower inner space of the processingchamber 11, electrodes 31, 32 provided above the mounting table 2 togenerate plasma P, and a gas shower head (gas supply unit) 4 disposedabove the electrodes 31, 32 to face the mounting table 2.

The processing chamber 11 is made of a metal, e.g., aluminum having asuperior cooling ability than ceramic or the like, and inner surfaces ofthe processing chamber 11 are coated and insulated with, e.g., alumite.Further, the processing chamber 11 has flow channels 12 for atemperature adjustment fluid F₁ at sidewalls thereof. The flow channels12 spirally extend along and within the periphery sidewalls of theprocessing chamber 11 from its upper portion to its lower portion asshown in an arrow of FIG. 1. Further, the apparatus 1 includes atemperature adjustment mechanism 35 for adjusting a temperature of theprocessing chamber 11. Here, the temperature adjustment fluid F₁circulates between the temperature adjustment mechanism 35 and theprocessing chamber 11. In this way, a coolant, e.g., cooling water asthe temperature adjustment fluid F₁ flows through the flow channels 12during the etching process, thereby controlling, e.g., decreasing thetemperature of the inner surface of sidewalls of the processing chamber11.

Moreover, a gas exhaust unit 14 including a vacuum pump and a pressureadjustment part is coupled through a gas exhaust line 15 to a gasexhaust port 13 provided in a bottom portion of the processing chamber11. The pressure adjustment part maintains the inside of the processingchamber 11 to a desired vacuum level according to a control signal froma controller 10 to be described later. A reference numeral 16 refers toa transfer opening provided in one sidewall of the processing chamber 11to convey a substrate B and the conveyance opening 16 is opened orclosed by a gate valve 17. A reference numeral 18 refers to a holdermade of an insulating material which surrounds and holds the electrodes31, 32 in a position above the mounting table 2.

The mounting table 2 has a rectangular shape corresponding to a shape ofthe substrate B and is supported by a support 21 located in a lowerportion of the processing chamber 11. Further, a lower electrode 22 isembedded into the mounting table 2. The lower electrode 22 applies abiasing potential to the substrate B and attracts ions generated from aprocessing gas G to be described later toward the substrate B, therebyimproving a vertical level of an etching shape. Moreover, the lowerelectrode 22 is connected to a RF power supply 32 of, e.g., 0.38 MHz to13 MHz which corresponds to a second RF power supply in the claims.

In addition, on outer periphery edges of the mounting table 2, a focusring 25 is installed so as to surround the substrate B. Duringgenerating plasma P, the corresponding plasma P is concentrated to thesubstrate B through the corresponding focus ring 25. A baffle plate 26having a shape of a square frame is installed at an outer periphery ofthe mounting table 2 and partitions the inner space of the processingchamber 11. The baffle plate 26 has a plurality of holes opened in adirection of thickness thereof to make a flow of the gas near thesubstrate B uniform while exhausting the inside of the processingchamber 11.

The mounting table 2 has therein flow channels 27 of a coolant, e.g.,cooling water as temperature adjustment fluid F₂. The cooling waterflows through the flow channels 27 to cool down the mounting table 2 andcontrol the temperature of the substrate B mounted on the mounting table2 to a desired level. Further, the mounting table 2 is provided with atemperature sensor (not shown) which senses the temperature of thesubstrate B on the mounting table 2.

Following is a description of the electrodes 31, 32 disposed above themounting table 2. FIG. 2 shows a transversal cross-sectional plan viewof the electrodes 31, 32 taken along a line A-A of FIG. 1. Theelectrodes 31, 32 have a comb shape. That is the electrodes 31, 32respectively have bases 31 a, 32 a and a plurality of teeth 31 b, 32 bwhich horizontally extend in parallel pattern from the bases 31 a, 32 a.The base 31 a of one electrode 31 and the base 32 a of the otherelectrode 32 are adhered to the opposite side surfaces of the holder 18and arranged to face each other in a horizontal direction. The teeth 31b of the one electrode 31 and the teeth 32 b of the other electrode 32are alternately disposed so that one tooth 32 b can extend along andbetween two neighboring teeth 31 b. The electrodes 31, 32 are made of,e.g., aluminum (Al) and their surfaces are coated with an insulatingmaterial, e.g., Y₂O₃. In this example, the electrodes 31, 32respectively correspond to first and second electrodes in the claimsand, hereinafter, will be named “comb electrodes 31, 32”.

As shown in FIG. 3, flow channel 33 of a coolant, e.g., cooling water astemperature adjustment fluid F₃ is formed in the comb electrode 31. Theflow channel 33 runs from one end of the base 31 a and is bent toward atip end of the adjacent tooth 31 b. Then, the flow channel 33 is bent insubstantially “u” shape at the tip end of the tooth 31 b to turn backtoward the base 31 a. In this way, the flow channel 33 is extendedthrough all the teeth 31 b to the other end of the base 31 a. Inaddition, although not shown in the drawings, the comb electrode 32 hasthe same flow channel as the flow channel 33 formed in the combelectrode 31. Meanwhile, during an etching process, the cooling water asthe temperature adjustment fluid F₃ flows through the flow channel 33 asshown by arrows in FIG. 3 to cool down the comb electrodes 31, 32. Forthe sake of convenience, the flow channel 33 is not depicted in FIGS. 1and 2.

The comb electrode 31 is connected to a plasma generating RF powersupply 33 having a frequency of, e.g., 13 MHz to 60 MHz, higher than afrequency of a biasing RF power supply 23, while the comb electrode 32is connected to ground. Although not shown in the drawings, the RF powersupplies 23, 33 are connected to the controller 10, and the RF powersupplied from each RF power supply to each corresponding electrode iscontrolled according to the control signal from the controller 10.

Following is a description of the gas shower head 4 as the gas supplyunit. In this example, the gas shower head 4 is made of ceramic, e.g.,quartz and forms the ceiling plate of the processing chamber 11.Moreover, the gas shower head 4 has therein a space 41 into which eachprocessing gas to be described later is supplied. Further, the gasshower head 4 includes a plurality of gas supply holes 42 formed in itslower surface, the gas supply holes communicating with the space 41 anddispersedly and supplying the processing gas G into the processing spaceof the processing chamber 11. That is to say, the gas shower head 4includes a plate shaped body 4A is located above the comb electrodes 31,32 and opposite to the mounting table 2, which has the plurality of gassupply holes 42. As shown in FIGS. 1 and 2, each of the gas supply holes42 is arranged to supply the processing gas G into gaps between theteeth 31 b of the comb electrode 31 and the teeth 32 b of the combelectrode 32.

A gas inlet line 43 is provided at a center region of an upper surfaceof the gas shower head 4 and penetrates through a center portion of theceiling plate of the processing chamber 11. At upstream side of the gasinlet line 43, there are a plurality of branch lines whose one ends areconnected to the gas inlet line 43, other ends of the branch lines areconnected to gas supply sources 44A, 44B, 44C storing CF₄ gas, O₂ gasand N₂ gas as the etching gas, respectively. Each of the branch lines isprovided with a valve and a flow rate controller which form a gas supplysystem 45. The gas supply system 45 controls the gas supply from each ofthe gas supply sources 44A, 44B, 44C, and a gas flow rate based on thecontrol signal from the controller 10.

The plasma etching apparatus 1 is provided with the controller 10comprising, e.g., a computer. The controller 10 includes a program, amemory, a data processing unit such as CPU and the like, where theprogram is programmed so that the controller 10 sends various controlsignals to each unit of the plasma etching apparatus 1 and, hence,performs each step of a plasma etching method to be described later toform a desired etching pattern on the substrate B. Further, the memoryincludes regions for storing processing parameters such as a processingpressure, a processing time, a gas flow rate, a power value, etc.Therefore, when the CPU executes each command of the program, theprocessing parameters are read out and the control signal correspondingto the each processing parameter is transmitted to each unit of theplasma etching apparatus 1.

The program (including a program related to a screen for inputting theprocessing parameters) is stored into a storage unit 19 such as aflexible disk, a compact disk, MO (Magneto-Optical) disk or the likeand, then, is installed into the controller 10.

Following is a description of operation of the plasma etching apparatus1. First of all, the cooling water flows through the flow channel 12 ofthe processing chamber 11 and each flow channel 33 of the combelectrodes 31, 32 to cool down the inner walls of the processing chamber11 and the surfaces of the comb electrodes 31, 32. In addition, thecooling water flows through the flow channel 27 of the mounting table 2to cool down the mounting table 2. Then, the gate valve 17 is opened andthe substrate B is transferred into the processing chamber 11 by atransfer mechanism (not shown). After the substrate B is mounted ontothe mounting table 2 horizontally, the transfer mechanism is removedfrom the processing chamber 11 and the gate valve 17 is closed.

When the coolant as the temperature adjustment fluid F₂ flows throughthe flow channels 27, the substrate B mounted on the mounting table 2 iscooled down to a predetermined temperature level. During this, the gasexhaust unit 14 exhausts a gas within the processing chamber 11 throughthe gas exhaust line 15 so that the inside of the processing chamber 11is depressurized to a desired pressure level. At the same time, aprocessing gas G which is a mixture of the CF₄ gas, the O₂ gas and theN₂ gas is supplied into the processing chamber 11 via spaces between thecomb electrodes 31, 32. Then, the RF power supplies 23, 33 are turnedon, e.g., simultaneously. Thus, the RF power is applied to the lowerelectrode 22 and, at the same time, the RF power is applied between theneighboring comb electrodes 31, 32.

FIG. 4 illustrates the state of the gas within the processing chamber 11and the plasma P when the RF power is applied to the lower electrode 22and, at the same time, the RF power is applied between the neighboringcomb electrodes 31, 32. In FIG. 4, each of the teeth 31 b, 32 b of thecomb electrodes 31, 32 is depicted schematically and large arrowsrepresent the processing gas G supplied between the comb electrodes 31,32. As above, the RF power is applied between the comb electrodes 31, 32so that a RF electric current flows between the comb electrodes 31, 32.Thus, the high frequency energy activates the processing gas G and,hence, the plasma P is generated between the comb electrodes 31, 32,which located far from the substrate B on the mounting table 2, as shownin a dotted line. Here, the generated plasma P is thecapacitively-coupled plasma referred to as a remote plasma having anelectron temperature of 3 eV to 4 eV. Further, because the gas exhaustunit 14 exhausts the gas at the lower side of the inside of theprocessing chamber 11, the generated plasma P goes down and away fromthe area where the electric field are formed. So the electrontemperature of the plasma P changes to 1 eV to 2 eV near the substrateB. In addition, a variety of ions contained the plasma P are attractedtoward the substrate B by applying the RF power to the lower electrode22, thereby performing an anisotropic etching on the substrate B.

After the RF power has been applied between the comb electrodes 31, 32and a predetermined time lapses, for example, the RF power supplies 23,33 are turned off to extinguish the plasma P and, at the same time, thesupplying of the CF₄ gas, the O₂ gas and the N₂ gas into the processingchamber 11 is stopped. Thereafter, the gas exhaust unit 14 exhausts theprocessing gas remained in the processing chamber 11. Next, the gatevalve 17 is opened, and the substrate B is removed from the processingchamber 11 by the transfer mechanism. Then, for example, subsequentsubstrate B of the same lot is transferred into the processing chamber11 to be subject to the etching process.

In the plasma etching apparatus 1, the RF power is applied between theteeth 31 b, 32 b of the comb electrodes 31, disposed in a horizontaldirection above the mounting table, so that the processing gas Gsupplied from the gas shower head 4 is converted to the plasma P. Then,the plasma P is attracted toward the mounting table 2 by the exhaustionperformed at the lower side of the processing chamber 11. In thismanner, the plasma P is generated in a location which is spaced apartfrom the mounting table and, hence, the electron temperature is lowernear the substrate B than near the comb electrodes 31, 32. Accordingly,the substrate damage by the plasma P is suppressed. Further, because thecomb electrodes 31, 32 for applying the plasma generating RF power andthe lower electrode 22 for applying the biasing RF power are separatedfrom each other, the RF power applied between the comb electrodes 31, 32does not affect the biasing RF power applied to the mounting table 2 forattracting the plasma P, thereby suppressing the distortion of thewaveform of the latter RF power. Thus, it is easy to control an energydistribution of ions near the substrate B and a ratio of ions/radicalsimplanted into the substrate B and, hence, substrate in-plane variationsand substrate to substrate variations of the processing are suppressed.

Further, according to the present invention, the plasma generatingelectric field is confined within the upper portion of the processingchamber 11, so that the waveform of the biasing RF power applied in thelower portion of the processing chamber 11 is not deformed unlike thecase of the parallel-plate electrode type plasma processing apparatus.For this reason, when waveform of the biasing RF power is adjusted, theion collision distribution (where the horizontal axis represents an ionenergy level and the vertical axis represents a collision frequency ofions into the substrate as described above) complies with the adjustedwaveform of the biasing RF power. Here, the examples of the waveforminclude a sine wave, a triangle wave, a square wave and the like, andthe parameters of the waveform include a voltage level, rising andfalling of waveform, and the like. Further, an adequate ion collisiondistribution in each process is obtained by adjusting the parameters ofthe waveform.

Additionally, the processing chamber 11 is made of a metal and thecooling water as the temperature adjustment fluid F₁ flows through thechannels formed in the sidewalls of the chamber 11, so that the controlof the temperature of the processing chamber 11 is easier than thecontrol of the temperature of a processing chamber made of ceramic orthe like whose heat capacity is higher than the metal. Further, becausethe cooling water as the temperature adjustment fluid F₃ cools down thecomb electrodes 31, 32, the stable plasma P is obtained. This help toperform a stable processing on the substrates B when the substrates Bare continuously processed. Moreover, because the temperature of theinner walls of the processing chamber 11 and the comb electrodes 31, 32can be controlled, the heat is not accumulated on the surfaces of them.For this reason, even when the processing gas G whose components arereadily deposited in a high temperature level is used, it is possible tosuppress occurrence of particles due to the deposits of the processinggas G.

Moreover, in this embodiment, the processing gas G is supplied downwardby the gas shower head 4 from above toward the entire substrate B, whichresults in an improved in-plane uniformity compared with the case ofsupplying the processing gas by nozzles. In addition, the processing gassupplied from the gas shower head 4 is subject to the uniform actions ofthe electric field to be converted to the plasma P which, in turn, issupplied to the substrate B. Accordingly, the variations of thedissociation level at which molecule of the processing gas G aredissociated into ions or radicals are suppressed unlike theabove-mentioned microwave plasma processing apparatus. As a result, thesubstrate in-plane variations of the processing and the variations ofthe processing between the substrates of the same lot can be suppressed.

Second Embodiment

Following is a description of a plasma etching apparatus 51 inaccordance with another embodiment as shown in FIG. 5. The pair of thecomb electrodes 31, 32 forming the first and second electrodes areprovided under the gas shower head 4 in the above-mentioned embodiment,whereas one of the first and second electrodes is formed as a part ofthe gas shower head (gas supply unit) 52 and the other is formed as acomb electrode in this embodiment. Therefore, one comb electrode isprovided under the gas shower head 52. In this etching apparatus 51,elements or units having the same configuration as them of theabove-mentioned etching apparatus 1 use the same reference numerals asthem of the etching apparatus 1.

The gas shower head 52 of the etching apparatus 51 is made of a metalsuch as aluminum or the like and the surface thereof is coated with aninsulating material such as Y₂O₃ or the like. Moreover, the gas showerhead 52 serves as the electrode connected to ground for generatingplasma P together with a comb electrode 55 connected to a RF powersupply 33 to be described later. In addition, a space 52 a is providedwithin the gas shower head 52 as in the gas shower head 4 of the firstembodiment, and the gas shower head 52 includes a plate-type body 52Chaving a plurality of gas supply holes 52 b.

Within the space 52 a of the gas shower head 52, a temperatureadjustment plate (a temperature adjustment mechanism) 53 for adjustingthe temperature of the gas shower head 52 is installed on the plate-typebody 52C. In the temperature adjustment plate 53, a plurality of holes53 a is provided in a direction of thickness thereof so as to overlapthe gas supply holes 52 b of the gas shower head 52. In addition, withinthe temperature adjustment plate 53, flow channels (not shown) for thecooling water as the temperature adjustment fluid are provided inpositions where the holes 53 a are not formed. During the etchingprocess, the cooling water flows through the flow channels to cool downthe gas shower head 52.

Under the gas shower head 52, the comb electrode 55 is provided via aninsulator 54. FIG. 6 is a perspective view of the insulators 54 and thecomb electrode 55. Reference numerals 55 a, 55 b refer to a base andteeth of the comb electrode 55 respectively. A configuration of the combelectrode 55 is the same as that of the above-mentioned comb electrode31 except for the number and thickness of the teeth 55 b. Further, flowchannels (not shown) for the cooling water as the temperature adjustmentfluid are provided within the comb electrode 55 like the comb electrode31. Thus, during the etching process, the cooling water flows throughthe flow channels to cool down the surfaces of the comb electrode 55.Moreover, the insulator 54 is made of, e.g. ceramic and has a comb shapematching with the comb electrode 55. Further, the processing gas Gsupplied from the gas shower head 52 flows toward the substrate Bthrough spaces between the teeth of the insulator 54 and spaces betweenthe teeth 55 b of the comb electrode 55.

The operation of the plasma etching apparatus 51 is similar with that ofthe plasma etching apparatus 1. Specifically, the substrate B istransferred into the processing chamber 11. Then, if the pressure of theinside of the processing chamber becomes a predetermined level, eachprocessing gas G is supplied into the gas shower head 52 as shown bylarge arrows in FIG. 7 and, at the same time, the RF powers are appliedfrom the RF power supply 23, 33 respectively. In this way, as shown in adotted line of FIG. 7, the plasma P is generated between a lower surfaceof the gas shower head 52 and the teeth 55 b of the comb electrode 55.Thereafter, ions in the plasma P are attracted toward the substrate B toetch the substrate B.

The etching apparatus 51 has the same effects and advantages as those ofthe above-mentioned etching apparatus 1. In addition, because the gasshower head 52 of the etching apparatus 51 is made of aluminum and iscooled down by the cooling water, the heat is not accumulated on the gasshower head 52 during the etching process and, hence, the influence ofthe heat on each substrate B is reliably suppressed, thereby suppressingvariations of the processing between the substrates B.

Third Embodiment

Following is a description of a plasma etching apparatus 56 inaccordance with a still another embodiment as shown in FIG. 8. Theplasma etching apparatus 56 includes a gas shower head 57 whoseconfiguration will be explained with reference to FIG. 9.

The gas shower head 57 has a plate-type body 57D and is made of the samematerial as that of the gas shower head (gas supply unit) 52 of thesecond embodiment, e.g., aluminum. One of the first and secondelectrodes is formed as a part of the gas shower head (gas supply unit)57 and the other is formed as a comb electrode 59 to be explained later.The gas shower head 57 is different from the gas shower head 52 in thata plurality of linear protrusions 58, which extend horizontally inparallel and spaced apart from each other, are arranged at a lowersurface of the plate-type body 57D. Further, a plurality of gas supplyholes 57 b are formed in the lower surface of the plate-type body 57Dbetween the linear protrusions 58 and in the lower surfaces of thelinear protrusions 58 in a direction of thickness of the gas shower head57 so as to communicate with a space 57 a of the gas shower head 57 intowhich the processing gas G is supplied.

Here, an electric power applied to the gas shower head serving as of thefirst or second electrode is high-frequency, therefore an electriccurrent flows only at the surface of the electrode, thereby causing anelectric potential difference between the surfaces of the gas showerhead 57. For this reason, a plurality of holes 57 c are formed in theperiphery edge portion of a main body of the gas shower head 57 so as topenetrate through the gas shower head 57 in a direction of thicknessthereof but not to communicate with the space 57 a. In addition, aplurality of holes 58 c are formed in the linear protrusions 58 so as topenetrate through the linear protrusions 58 horizontally but not tocommunicate with the gas supply holes 57 b. Thus, the electric currentflows at the surfaces of the holes 57 c, 58 c and, hence, the electricpotential becomes uniform in the entire surfaces of the gas shower head57. Further, for this reason, when a RF power is applied to the combelectrode 59 to be described later and the plasma P is generated betweenthe gas shower head 57 and the comb electrode 59, a density of thegenerated plasma P becomes uniform. In view of this, holes having thesame function as that of the holes 57 c, 58 c may be also made in thecomb electrode 59 and, further, made in the first electrode and/orsecond electrode of the above-mentioned embodiments or embodiments whichwill be illustrated below.

The comb electrode 59 connected to a RF power supply is installed underthe gas shower head 57. The comb electrode 59 includes a base 59 a and aplurality of teeth 59 b which extend in parallel with each otherhorizontally from the base 59 a. The base 59 a of the comb electrode 59is supported, for example, by an insulating member fixed onto an innerwall of the processing chamber 11 and the teeth 59 b are arrangedvertically opposite the respective linear protrusions 58 of the gasshower head 57. The comb electrode 59 is made of, e.g., the samematerial as that of the comb electrode 31.

The operation of the plasma etching apparatus 56 is similar with thoseof the above-mentioned plasma etching apparatuses. Specifically, whenthe RF powers are applied from the RF power supplies 23, 33 whilesupplying each processing gas G into the gas shower head 57, the plasmaP is generated between the linear protrusions 58 of the gas shower head57 and the teeth 59 b of the comb electrode 59 as shown by a dotted linein FIG. 10. Thereafter, ions in the plasma P are attracted toward thesubstrate B to etch the substrate B. Meanwhile, the etching apparatus 56has the same effects and advantages as those of the above-mentionedetching apparatus 1. In addition, the gas shower head 57 and the combelectrode 59 of the etching apparatus 56 are made of aluminum. In thisway, except for a surface coating, no member made of a material having ahigher heat-accumulation property such as the ceramic is installed inthe processing space, so that the influence of the heat on the substrateB is suppressed. Moreover, flow channels of the cooling water as thetemperature adjustment fluid may be provided within the comb electrode59 as in the comb electrode 31, and the temperature adjustment plate 53of the second embodiment may be installed in the space 57 a of the gasshower head 57, thereby cooling down the comb electrode 59 and the gasshower head 57.

Fourth Embodiment

Following is a description of a plasma etching apparatus 6 for etching acircular type substrate, e.g., a wafer W. In this description,differences between this plasma etching apparatus 6 and theabove-mentioned plasma etching apparatuses are mainly described withreference to FIG. 11. A processing chamber 61 of the plasma etchingapparatus 6 has a cylinder shape and a mounting table 62 for mountingthereon the wafer W has a circular shape. Moreover, the gas shower head(gas supply unit) 63 has the same configuration as that of the gasshower head 4 of the above-mentioned first embodiment except that theformer has a circular shape so as to match with the shape of theprocessing chamber 61. In addition, a plurality of gas supply holes 63 bcommunicating with an inner space 63 a of the gas shower head 63 areprovided in a lower plate of the gas shower head 63 to supply theprocessing gas G into between the electrodes to be described later.

The gas shower head 63 includes a plate-type body 63C, and, under theplate-type body 63C, a group of electrodes is provided as shown in FIG.12. The group of electrodes includes, e.g., an electrode 64 a installedin a center axis of the mounting table 62 and ring-shape electrodes 64 bto 64 d which are spaced each other and disposed concentrically aroundthe electrode 64 a. Further, the electrodes 64 a, 64 c are connected toa RF power supply 33, while the electrodes 64 b, 64 d are connected toground. The electrodes 64 a, 64 c correspond to one of the first andsecond electrodes and the electrodes 64 b, 64 d correspond to the other.Each of the electrodes 64 a to 64 d is made of, e.g., the same materialas that of the comb electrode 31.

The operation of the plasma etching apparatus 6 is similar with those ofthe above-mentioned plasma etching apparatuses. Specifically, the waferW is transferred into the processing chamber and a plasma p is generatedbetween the electrodes 64 a to 64 d to etch the wafer W. Further, acircumference length of the wafer W gets larger as it goes away from thecenter of the wafer. Accordingly, in order to make an electric fieldlevel distribution in a radial direction of the wafer W uniform, thedistance between the neighboring ring-shape electrodes 64 b to 64 d getssmaller as it goes away from the center of the wafer. In other words, asshown in FIG. 11, when the distance between the electrodes 64 a and 64b, the distance between the electrodes 64 b and 64 c, and the distancebetween the electrodes 64 c and 64 d are respectively represented by d₁,d₂, and d₃, a relationship between d₁, d₂, and d₃ becomes d₁>d₂>d₃. Inthis way, a plasma density distribution in the radial direction of thewafer W becomes uniform. Meanwhile, the etching apparatus 6 has the sameeffects and advantages as those of the above-mentioned etching apparatus1.

Fifth Embodiment

FIG. 13 depicts another embodiment of the plasma etching apparatus foretching a wafer W. The gas shower head 71 of this plasma etchingapparatus 7 has a circular shape so as to match with the shape of theprocessing chamber 61. Further, a protrusion 72 a is formed at the lowersurface of a plate-type body 71A of the gas shower head 71 in the centeraxis of the mounting table 62. In addition, ring-shaped protrusions 72b, 72 c which are spaced each other and disposed concentrically aroundthe protrusion 72 a are formed at the lower surface of the plate-typebody 71A of the gas shower head 71. Further, ring-shape members 73 a, 73b serving as the electrodes are formed between the protrusions 72 a and72 b, and between the protrusions 72 b and 72 c respectively.

FIG. 14 shows a configuration of the protrusions 72 a to 72 c and thering-shape members 73 a, 73 b. The ring-shape members 73 a, 73 b aresupported by the protrusions 72 b, 72 c respectively through supportingmembers 74 a, 74 b made of, e.g., an insulating material such asceramic. That is, this embodiment has the modified configuration of thefourth embodiment in that one of the set of the ring-shape electrodes 64a, 64 c and the set of the ring-shape electrode 64 b, 64 d in the fourthembodiment is formed at the lower surface of the gas shower head 71 tohave the same electric potential as that of the gas shower head 71.Therefore, the protrusions 72 a to 72 c and the gas shower head 71correspond to one of the first and second electrodes, while thering-shape members 73 a, 73 b correspond to the other one. For example,the protrusions 72 a to 72 c are connected to ground and the ring-shapemembers 73 a, 73 b are connected to the RF power supply 33.

Further, in the first embodiment for the rectangular type substrate, oneof a group of the teeth 32 b of the comb electrode 32 as rod-shapedmembers corresponding to the first electrode and a group of the teeth 31b of the comb electrode 31 as rod-shaped members corresponding to thesecond electrode may be formed at the lower surface of the gas showerhead 4 as in FIG. 13 and the gas shower head 4 may be made of metal. Inthis case, an electric potential of one of two groups of the teeth 31 b,32 b may be same as that of the gas shower head 4 as in the fifthembodiment.

Sixth Embodiment

A plasma etching apparatus may be configured as in FIG. 15. Theconfiguration of the etching apparatus 8 in FIG. 15 is the same as thatof the etching apparatus 6 of the fourth embodiment in FIG. 11 exceptfor the configuration of the electrodes. FIG. 16 is a perspective viewof the electrodes where a plurality of rod-shaped electrodes 81 extendshorizontally in parallel with each other under a plate-type body 63A ofa gas shower head 63. Further, under the electrodes 81, a plurality ofrod-shaped parallel electrodes extend in a perpendicular direction tothe extending direction of the electrodes 81, with insulating members 82being interposed between the electrodes 81, 83. In this way, theelectrodes 81, 83 are arranged to form a lattice pattern. The processinggas is supplied from gas supply holes 63 b of the gas shower head 63through spaces between the electrodes to generate the plasma P.

In each of the above-mentioned embodiments, among the first and secondelectrodes, the electrode connected to a ground and the electrodeconnected to the plasma generating RF power supply 33 may be exchanged.Moreover, other well-known etching gases than the above-mentionedetching gases may be used. Further, the plasma processing apparatus inaccordance with the present invention may be applied not only to theetching apparatus but also to a CVD apparatus, a sputtering apparatus orthe like using the plasma.

What is claimed is:
 1. A plasma processing method using a processingapparatus having a processing chamber for processing a substrate by aplasma of a processing gas, the method comprising: mounting thesubstrate onto a mounting table provided in a lower portion of theprocessing chamber; supplying the processing gas between a firstelectrode and a second electrode provided in an upper portion of theprocessing chamber, wherein the first electrode has a first plurality oflinear members horizontally extending in parallel with each other andthe second electrode has a second plurality of linear membershorizontally extending in parallel with each other, the first pluralityof linear members being arranged in a one-to-one corresponding mannerwith the second plurality of linear members and each of the firstplurality of linear members being vertically opposite the correspondingone of the second plurality of linear members; applying an RF powerbetween the first electrode and the second electrode so that theprocessing gas supplied between the first electrode and second electrodeis converted to the plasma of the processing gas; and exhausting theinside of the processing chamber from a lower portion of the processingchamber to a vacuum level.
 2. The plasma processing method of claim 1,wherein the processing gas is supplied between the first electrode andsecond electrode through a plurality of gas supply holes formed througha plate-shaped body that is located above the first electrode and secondelectrode.
 3. The plasma processing method of claim 1, wherein saidapplying the RF power between the first electrode and the secondelectrode includes applying the RF power to the second electrode withthe first electrode grounded.
 4. The plasma processing method of claim1, wherein the first electrode is disposed above the second electrode.